It isn't Webster's, but that's a passable makeshift definition for the title of The Wackness, a movie that — like its hero — struggles to assert itself in the midst of crushing depression. At its best, it touches on the awkward yearnings and sudden emotional switchbacks of two well-meaning New York misfits, circa 1994. One is Luke (Josh Peck), a mopey but decent drug dealer who just graduated high school and plans to spend the summer before college selling weed. The other is his shrink, the addled and straggle-haired Jeffrey Squires (Ben Kingsley), who swaps therapy sessions for marijuana.

Luke dwells on his screwed-up existence and pines for Squires' cold but fetching stepdaughter, Stephanie (Olivia Thirlby), wooing her with malt 40s and good-old-fashioned amorous cow eyes. Squires self-medicates his own chasmal unhappiness. In this manner the movie passes, marked off by months emblazoned in graffiti. Doctor and patient — but which is which? — meander from crisis to crisis, from sodden revelation to sodden revelation, until everything crashes on a beach in dangerous emotional territory.

On the dope side: Kingsley makes a deliciously sloppy beatnik. Keep your eyes peeled for Mary-Kate Olsen in a small, crazed part as an osculating hippie chick. Sweltering nineties hip-hop (Notorious B.I.G., the Wu-Tang Clan) cuts through Luke's life and the movie's soundtrack, offsetting all those what-ups and peace-outs and Beverly Hills, 90210 references busying the script. And Levine tosses in a few fanciful comic touches — Luke, dancing and giddy in love, illuminates a sidewalk step-by-step — that lift the film's mood and suggest the work of an inventive visual stylist.

On the downside: There is a wackness to The Wackness, a saggy psychic undertow that drags down its lighter and smarter aspects. The whole thing slouches like a teenager. This wan indie coming-of-age tale from writer-director Jonathan Levine (who helmed All the Boys Love Mandy Lane, a more murderous view of adolescence) suffers from an attitudinal malaise that saps its own energy while it's piling on the period lingo. The overall look of the film is muted to the point of glum: Petra Korner's cinematography has the washed-out palette of a vintage T-shirt collection. Sure, it's a film about chronic melancholy. But that doesn't mean it has to look the part.

And Peck, I'm afraid, was underdirected. A Nickelodeon veteran (Drake & Josh) now breaking into mature roles, he does not lack talent or charisma — his scenes with Thirlby are sweet, clumsy and credible — but he spends too much of The Wackness in attitudes of hangdog lethargy. It's not his fault. Pin the blame on Levine, who too often confuses depression with teenage ennui and epiphany with chemically altered states.

The parallels between Luke's woes and his doctor's are clear enough: Luke has messed-up parents, Squires has a sharp, dismissive wife (Famke Janssen). Luke pushes his ice cart filled with dime bags; Squires pushes his half-baked prescriptions for sex and self-fulfillment ("Sometimes it's right to do the wrong thing"). Neither really believes in his wares, but it's a living.

Or is it? Though drugs and alcohol are consumed just about nonstop in The Wackness, Levine isn't hawking either one — or self-loathing — as an alternative lifestyle. His protagonists are lonely — that's the main thing. They're confused — that's another. Luke and his nutcase psychiatrist are both glass-half-empty kind of people, pessimists who grasp for a reason to live and find it, maybe, in each other. "I look at the dopeness," says Stephanie to Luke. "But you — you just look at the wackness." No matter how it's defined.